#include <stdio.h>


signed main() {
    int a = 1, b = 3; // (a / b == 1 / 3)
    int c = 4, d = 7; // (c / d == 4 / 7)
    a = a * c; b = b * d; // (1 / 3) * (4 / 7) == (a * c) / (b * d)
    // 此时a == 4, b == 21, a / b == 4 / 21
    return 0;
}